The existing way to monitor discovery information in a wireless communication system supporting device-to-device (D2D) discovery will be described with reference to FIG. 1.
FIGS. 1 and 2 illustrate the existing discovery information monitoring method in a wireless communication system supporting D2D communication according to the related art.
Referring to FIG. 1, discovery information may be transmitted on a discovery channel 101 by a proximity service (ProSe) user equipment (UE) (which supports a ProSe service or a D2D service, like discovery or communication). The ProSe UE may refer to a UE that uses a proximity service like the D2D service. The D2D service may be construed to include a variety of proximity services.
The ProSe UE interested in discovering other ProSe UEs may monitor the discovery information in which the ProSe UE is interested.
The ProSe UE may monitor the discovery channel(s) 101 for receiving the discovery information.
During the monitoring, the discovery channel 101 may be received and decoded by a physical (PHY) layer 111.
A discovery protocol data unit (PDU) 103 received in the discovery channel 101 may be processed (e.g., security-processed) by a protocol stack 113 of a user plane or control plane, and then, the discovery information may be sent to an application layer 115.
Applications 115-1, 115-2, . . . , 115-n in the application layer 115 or a ProSe manager 115a may determine whether a received discovery code/information 105a corresponds to an interest/user information 105b of the ProSe UE.
However, there are several issues in monitoring the discovery information in the existing system described in FIG. 1. The issues in a discovery information monitoring procedure in the existing system will be described with reference to FIG. 2.
Suppose that an application layer in a UE monitoring discovery information triggers to monitor the discovery information (e.g., a discovery code ‘x’) at time ‘t’ (201) as illustrated in FIG. 2. In this case, the PHY layer in the UE may start monitoring a discovery channel. The discovery code ‘x’ may be received after time ‘t+monitoring duration 203 (205). In the example of FIG. 2, the UE may monitor four discovery sub-frames (SFs), each carrying N discovery channels. As a result of the discovery information monitoring procedure described earlier, the physical layer 111 in FIG. 1 may receive and decode a plurality of discovery physical channels (hereinafter, referred to as ‘discovery channels’) 101, in the situation of FIG. 2. The protocol stack 113 of the user plane or control plane may process many a plurality of discovery PDUs 103. In this case, the protocol stack 113 of the user plane or control plane may wake up the application layer 115 many times.
In the existing discovery information monitoring method, the UE may continuously monitor and decode all discovery channel resources for receiving and decoding the discovery physical channel. The protocol stack of the user plane or control plane of the UE may process each and every discovery PDU received on the discovery physical channel, and send the received discovery information to the application layer. Therefore, the application layer of the UE may be waked up every time a discovery PDU is received by the protocol stack of the user plane or control plane.
Therefore, the existing discovery information monitoring method may increase the processing burden of the UE in the process of transmitting and receiving discovery information, and may also increase the power consumption.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.